This invention relates to integrated circuits, and more particularly, to programmable integrated circuits.
Programmable integrated circuits are a type of integrated circuit that can be programmed by a user to implement a desired custom logic function. In a typical scenario, a logic designer uses computer-aided design (CAD) tools to design a custom logic circuit. These tools help the designer implement the custom logic circuit using the resources available on a given programmable integrated circuit. When the design process is complete, the CAD tools generate configuration data files. The configuration data is loaded into programmable devices to configure them to perform the desired custom logic function.
Power consumption is a critical challenge for modern integrated circuits such as programmable integrated circuits. Circuits with poor power efficiency place undesirable demands on system designers. Power supply capacity may need to be increased, thermal management issues may need to be addressed, and circuit designs may need to be altered to accommodate inefficient circuitry.
One way of improving power efficiency involves power gating different groups of circuits on an integrated circuit. For example, a programmable integrated circuit may include different groups of circuits organized according to their functionality and may include power gating circuitry for selectively powering the different groups of circuits. In particular, a first power gating transistor on the programmable integrated circuit may be used to supply power to a first group of circuits, whereas a second power gating transistor on the programmable integrated may be used to supply power to a second group of circuits. In this example, the first power gating transistor can be turned off to deactivate the first group of circuits while the second power gating transistor is turned on to activate the second group of circuits. Selectively activating/deactivating the different groups of circuits on the programmable integrated circuit can help improve power efficiency.
Each power gating transistors is typically formed adjacent to an associated group of circuits. As an example, the first power gating transistor that controls the first group of circuits is placed in a region on the integrated circuit in which the first group of circuits is formed. Accordingly, the area of a particular region may need to be sufficiently sized to accommodate the placement of the power gating transistors. Furthermore, each of the power gating transistors may need to be sufficiently large to mitigate potential IR drop (also known as voltage drop) problems. As such, additional area on the integrated circuit may need to be reserved for the power gating transistors and associated control circuitry that is used to selectively turn on and off the power gating transistors.